Traditional microwave detector designs use resistive terminations to match an RF source. However, the detector diodes used in such designs, when operated unbiased or at a small DC bias, have a relatively high RF resistance and receive only a small fraction of the available signal power when connected in parallel to the resistive termination (e.g. a 50 ohm resistor).
In narrow band applications, high sensitivity tuned detectors are preferred. Impedance transformation and reverse-phasing of the detector diode terminals have been used to increase the sensitivity and output voltage of the resistive termination used in such prior art designs. Nevertheless, both techniques have deficiencies. The first technique makes use of circuit elements such as quarter-wave high impedance transmission lines, which are difficult to achieve with conventional lines. The second technique requires a 180.degree. power divider. The requirement for additional elements to implement these two prior art techniques increases the complexity and size of the detector assembly and introduces extra losses.